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Re: Boot poster challenge



On Sun, Nov 21, 2004 at 04:55:47PM +0100, Arjan van de Ven wrote:
> 
> On Sun, Nov 21, 2004 at 10:42:45AM -0500, Alan Cox wrote:
> > On Sat, Nov 20, 2004 at 11:50:49PM +0100, Ziga Mahkovec wrote:
> > > This chart includes data from iostat (sysstat package).  Notice how the
> > > disk is fully utilized (%util) during readahead, but the throughput
> > > (rkB/s) is *really* low.  This could very well be a problem with my hard
> > > disk.  hdparm seems fine though (and I checked the parameters before
> > > running readahead).
> > 
> > Disks are very very seek constrained. You get wonderful performance reading
> > linear data. The moment you read a lot of scattered files or a file with a
> > lot of segments you will get low performance - even more so on laptops than
> > desktops
> 
> yeah we saw that; sorting the list on disk sector shaved 2 seconds off...
> if we want to save more we'll have to fix the on disk layout to be less
> spread out. That's not going to be fun...

Is it possible to get a list of the sectors read for each file, instead
of only the file name?

Or do you expect that, for each file read, it will be read almost
entirely?

Regards,
Luciano Rocha

-- 
Consciousness: that annoying time between naps.


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